Removed test code, moved config code, changed around some documentation.

Removed the unneeded test code from the network/client.py and
network/servery.py modules.

Moved all configuration code to todo_config.py since todo.py and
todo_server.py were overlapping a bit. Changed the configuration
behavior such that it uses files in this order: file specified by -f,
~/.todo, /etc/todo.conf. If none of these files exist and a write with
-w is specified it defaults to ~/.todo so that the write can occur.

Changed the documentation for -w to reflect the behavior described
above.